my head in a jar

I am a member of Planet Informatics so everything I post also gets put on that web page too. One thing I've noticed is that everyone who posts gets a little picture of their head in a jar (similar to Futurama) next to what is written. I seem to be the only member who does not get a picture by what I write. Is it b/c my friends really don't like?? Perhaps they are trying to forget who I am and what I look like?? Maybe they realize that I'm an alien, and not in the sense of foreign to the US, and think my identity needs to be kept secret.

What does one need to do to get their head in a jar???